1. Technical Field
This application relates to a control and display device and, in particular, to a protective covering for the device.
2. Description of Related Art
Devices, such as portable control and display devices, are generally known in a plurality of embodiments, for example, as measuring instruments. These instruments may be used in the food industry and in food processing plants such as, for example, slaughterhouses, refrigeration plants, restaurants, and the like. Instruments that may be used, for example, in the food industry and in areas related to food processing, may be required to comply with certain hygienic requirements and other regulatory requirements such as those set forth in national and international regulations. These requirements may relate to the cleanliness of the instruments, such as measuring instruments. The requirements may relate to, for example, prevention of contamination, such as, bacterial contamination, of the measuring instruments.
In order to avoid such contamination, the instruments may include protective devices. These protective devices are used for hermetically sealing the measuring instruments against water, dust, and similar contamination in a way so that the functionality and operability of the instrument are not affected by the protective device. One type of protective device includes flexible, mostly transparent, bag-type protective sheathings. These sheathings may, more or less, protect the instrument from water, dust, and the like. The functionality and operability of the instrument protected by the protective sheathing remain preserved thanks to the flexible sheathing. However, these flexible protective sheathings may be made of a relatively thin plastic material. The functionality of such protective sheathings may be reduced over time due to the rough operating conditions to which the measuring instruments may be exposed. Under extreme operating conditions, there is also the danger that the instrument may become damaged due to the effect of external forces, since the thin protective sheathing may be extremely sensitive to impact and forces. In other words, the protective sheathings may not be able to absorb such forces thereby possibly resulting in damage to the instrument.
Another disadvantage of these known protective sheathings is the fact that even the slightest damage to the protective sheathing surface may result in impairing the required water-tightness. This may subsequently irreversibly damage or destroy an electronic component that may be included in the instrument, and may be sensitive to moisture. Furthermore, once the instrument is in the protective sheathing, it cannot be attached to a bracket provided, and external components cannot be attached to the instrument.
German Patent Application 39 05 130 A1 describes an improved protective device for a measuring instrument. In contrast to the foregoing bag-type protective sheathing, German Patent Application 39 05 130 A1 describes a cover-like shield made of a non-deformable material used as a protective device. The shield covers the control and display elements arranged in the housing, thus protecting them. In order to attach the cover to the housing, fastening elements are provided. To ensure tightness, an integrated sealing lip is provided around the housing part of the measuring instrument. The shield that covers and seals the control and display elements is transparent at least in the areas of the above-named display and control elements.
As an alternative, it is also conceivable to design the protective device as a two-part protective housing (holster). An internal contour of the protective housing may be designed so that the measuring instrument can be placed inside with essentially no play, and the two protective housing parts held together by fastening elements.
Although the protective device designed as a non-deformable shield and the protective housing designed as a holster have a high degree of water-tightness when used with a control and display device, providing protection against the effect of outside forces, there may still remain problems and drawbacks.
Manufacturing costs may be substantially increased since the measuring instruments to be used in the aforementioned areas requires an additional protective housing. Even in this case, it is not possible to use a shield made of a very soft material, for example, a plastic, since such material does not have the rigidity required to obtain an effective seal or, alternatively may have this property only under certain conditions. Therefore, a two-component part having high rigidity may be used in order to obtain the required impact-absorbing soft surface. This may be, however, unacceptable due to the high cost involved.
Due to the sealing lip around and integrated in the housing part, a large surface is sealed. This may be very expensive especially when a tight seal is required. Therefore, often a plurality of support points, for example, screws or clamps, may be required and may result in an inability to obtain the required high degree of tightness. For example, screws must be perfectly tightened to obtain a tight seal in an effort to prevent gaps, and thus untightness, from occurring. In particular, when the screws are frequently removed from the measuring instruments, this gap-free seal becomes more and more difficult to guarantee.
Additionally, sealing forces and joining forces act in the same direction when the shield is mounted on the housing. Accordingly, higher sealing forces may be required to be applied for a good seal than in an alternative instance when the forces do not act in parallel. Undesirable tolerances and slack may be poorly compensated for, or not at all, when the shield is mounted on the measuring instruments due to the close geometric relationship between the shield and the measuring instrument.
Failure to use such a protective housing in the aforementioned cases for reasons of time or convenience or due to lack of tools for fastening the fastening means may occur, and the measuring instrument used may not be able to be cleaned in a convenient and, mainly, reliable manner in a cleaning machine.
An additional condition in handling the aforementioned measuring instruments is the high hygienic requirements. In the aforementioned fields of application of the instruments provided with such protective housings, different cleaning procedures are used. It has been found that cleaning procedures, for example, such as one using a wet but not previously used cleaning cloth, a disposable cloth, a cleaning agent (RIX), or a cleaning agent with subsequent alcohol disinfection, clean the instruments, more or less well. However, complete, one-hundred-percent cleaning cannot be assured with these cleaning procedures. Only when instruments are cleaned in a cleaning machine for 45 minutes at a temperature of 75 degrees Celcius is one hundred-percent cleaning effect achieved with both non-fatty and fatty contamination.
In order to reliably meet the required hygienic requirements, it is therefore desirable to subject the instruments to cleaning in a cleaning machine.
The invention provides a control and display device ensuring a relatively high degree of tightness, in particular, water-tightness. This is achieved according to the present invention by a control and display device which includes a single one-piece housing made of a temperature-resistant material, which seals the control and display device in a water-tight manner from the outside.
The present invention is based on the idea of integrating previously used multi-part additional protective housings into essentially one housing for a measuring instrument. This measuring instrument therefore includes a single, impact-resistant and water-tight housing, which may be a fixed component of this measuring instrument. Advantages of this measuring instrument, compared with known, two-part or multi-part, measuring instruments that require a water-tight housing (holster, shield) for use in wet environments, include low manufacturing costs.
An embodiment of the single-part housing is also very safe for the process concerning tightness since no screws are used that have to be perfectly tightened. Since the housing may be made of a temperature-resistant material and provide for a seal from the outside in a water-tight manner, it is suitable for cleaning with hot water of at least 75 degrees Celcius. Thus the housing may be cleaned in a cleaning machine in a simple manner, whereby the highest possible degree of disinfection is guaranteed.
The control and display device according to the present invention ensures not only the highest possible degree of water-tightness, but also very effective protection against impact and contamination is achieved at the same time.
Due to its elasticity and its shape, the housing fits the shape of the sleeve in an almost form-fitting manner. Thus no gap may occur between the housing and the sleeve, whereby the arrangement according to the present invention also provides for compliance with hygienic requirements.
In the case of a defective housing and/or a defective measuring instrument, the housing may be detached from the measuring instrument in a simple manner and, if necessary, replaced with a new housing. After checking and, if needed, repair, an instrument that gives the visual impression of being new may be provided by replacing the housing.
According to one embodiment of the present invention, the housing encloses a sleeve in which the circuit board, the indicator panel, the keyboard, or at least the contact-sensitive areas of the keyboard, are accommodated. This sleeve may be designed in the form of a box and may be closed on one or more sides by a cover. The sleeve has the function of supporting, as well as accommodating, the aforementioned elements of the measuring instrument. In another embodiment, the sleeve may be omitted, if, for example, the housing itself assumes the protective function. In this instance, the housing may have one or more support braces.
One advantage of the housing according to the present invention is that the housing may be mounted on the sleeve without tools while still achieving a high degree of tightness. This may be particularly advantageous if, for example, the measuring instrument used for on-site measurements cannot be cleaned. In this case, a plurality of clean, i.e., disinfected, housing sheathings may be used, for example, and substituted for the used housing sheathings.
Another advantage that may be achieved using the present invention is that the directions of the joining force and the sealing force may be perpendicular to one another. In order to achieve a high degree of tightness, relatively small sealing forces are sufficient for sealing. Since sealing occurs perpendicularly to the direction of joining with almost no force, no fastening elements such as screws or clamps are required here, which may reduce development and manufacturing time, sealing surfaces and therefore fastening material and sealing material costs.
The sealing device between sleeve and housing may be implemented using, for example, a peripheral groove or a peripheral ridge, applied to the sleeve or the housing so that the ridge engages in the groove when the sleeve and the housing are joined together. In this instance, a particularly good sealing effect may be achieved between the two parts by the use of an elastic material in conjunction with an at least slightly larger groove compared to the ridge. The sealing effect of the sealing device between the sleeve and the housing may be further enhanced by applying sealing lips on the groove and/or the ridge.
In another embodiment of the sealing device, a plug or a ring, advantageously reinforced by braces, is provided, which is pushed into the housing that is open on one side. This ring or plug may be attached to a cover, to the sleeve, or to the housing. This ring or plug may be have pointed pins, nubs, peripheral ribs, or wedges, which engage in the softer material of the jacket on the opposite side or press on the harder material by deformation to achieve a good sealing effect. In these cases, cylindrical rings or plugs, which taper slightly in the direction of insertion, may be used to achieve a sealing effect. The sealing device may also include a snap-in detection device to ensure reliable engagement of the ridge in the groove, or of the plug, or ring, in the housing, or the sleeve.
A more or less soft plastic, such as an elastomer, may be used as the housing material in accordance with the application and the need. This plastic material may have the required impact-absorbing rigidity required for sealing and protection, as well as the soft surface for the functionality of the keys to be pressed. The housing may be made, at least in part, of a TPU, TPE, or PVC material. An injection molded part that may be easily and inexpensively manufactured, may be used as the housing.
In using such materials, for example, soft PVC or thermoplastic TPU, a fully transparent housing may be used in an embodiment. However, an alternative embodiment may include a housing of a semi-transparent material. The use of transparent or semi-transparent materials may-result in ease of reading characters, for example, those included on the indicator panel, the keyboard, and/or additionally, markings on the sleeve. In an embodiment, the housing may also be manufactured of a non-transparent, colored material. In this case, a transparent protective sight glass may be provided in the area of the indicator panel.
The housing may be an elongated plastic hose having the same diameter as, or a slightly larger diameter than, the sleeve of the measuring instrument. In this case, assembly may be performed as by pulling the hose over the measuring instrument and providing it with suitable sealing devices at its open ends. The adhesive forces may be provided by the adhesion of the hose having a larger size to the sleeve. When a hose is used, advantageously little or no tool costs may be involved.
According to another embodiment of the present invention, the housing includes a number of push rods corresponding to the number of keys in the keyboard area. The push rods raise outward over the surface of the housing. The control area or the keyboard of the measuring instrument may also be formed by a housing section having a reduced wall thickness. In this case, the control area may be manufactured in one piece with the housing from the same material.
In another embodiment, recesses may be provided, on the side facing away from the control area or the keyboard. These recesses may be used for attaching the device to a corresponding bracket. To achieve increased rigidity in use and improved handling of the housing, in another embodiment of the device at least one reinforcing strip is provided, which is made of the same material as the housing. The reinforcing strip furthermore may provide increased protection of the circuit board located inside the sleeve against forces acting from the outside.
The sealing effect in the area of an opening may be ensured by matching the shape and size of the opening to the shape and size of the plug, so that the housing is in contact with the plug over the entire surface of the latter and thus in a water-tight manner. In another embodiment, a sealing lip is provided in the opening, which is in a linear peripheral contact with the plug passing through it, thus providing a water-tight seal. This variant has the advantage that the plug may be inserted in the opening using little force. The opening may be closed with an appropriate cap when no plug is used.